Wolfgang Ketterle
Department of Physics, MIT-Harvard Center, USA
Date
22 September 2010
Host
Tilman Esslinger
Title
Towards Quantum Magnetism with Ultracold Atoms
Abstract
Over the last 20 years, science with ultracold atoms has focused on motion: slowing down motion, population of a single motional state (Bose-Einstein condensation, atom lasers), superfluid motion of bosons and fermion pairs. In my talk, I will address the next challenge when motion is frozen out: Spin ordering. A two-component boson or fermion mixture can form magnetic phases such as ferromagnetic, antiferromagnetic ordering and a spin liquid. The challenge is to reach the low temperature and entropy required to observe these phenomena. I will describe our current efforts and progress towards this goal. This includes the study of fermions with strong repulsive interactions where we obtained evidence for a phase transition to itinerant ferromagnetism, the study of atomic density fluctuations and a new adiabatic gradient demagnetization cooling scheme which has enabled us to realize spin temperatures of less than 50 picokelvin in optical lattices. These are the lowest temperatures ever measured in any physical system.